title: Anatomy- vs. fluence-based planning for prostate cancer treatments using VMAT.
abstract: The purpose of this study was to compare the planning approaches used in two treatment planning systems (TPS) provided by Elekta for VMAT treatments. Ten prostate patients were studied retrospectively. Plan comparison was performed in terms of delivery efficiency and accuracy, as well as in terms of target coverage and critical organ protection by utilizing physical and radiobiological indices. These include: DVH (dose volume histogram) values, CI (conformity index), HI(%) (homogeneity index) and TCP (tumor control probability) for target coverage; mean doses, DVH values, dose to the normal non-target tissue, NTCP (normal tissue complication probability) and GI (gradient index) for critical organ sparing; MU/fraction and treatment time for delivery efficiency. The comparisons were performed using the two-sided Wilcoxon matched-pair signed rank test. Plans generated using the anatomy-based approach in ERGO++ and fluence-based approach in Monaco were found similar in terms of target coverage and TCP values, as well as in terms of rectum protection and corresponding NTCP values. The former exhibited increased delivery efficiency (comparable to that of 3D conformal radiotherapy) due to the relatively larger segments used. On the other hand advantages of the fluence-based approach in Monaco include increased conformity, better target dose homogeneity and higher dose gradient (lower dose to normal non-target-tissue) mainly due to the higher degree of modulation offered by the fluence-based approach, while the Monte Carlo algorithm used for dose calculation provides plans with increased accuracy despite the relatively small segments used.
authors.affiliation: Medical Physics Laboratory, Medical School, University of Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Andreou
authors.affiliation: Medical Physics Laboratory, Medical School, University of Athens, Greece; Medical Physics Department, Hygeia Hospital, Athens, Greece. Electronic address: pkaraisk@med.uoa.gr.
authors.forename: Pantelis
authors.initials: P
authors.lastname: Karaiskos
authors.affiliation: Medical Physics Laboratory, Medical School, University of Athens, Greece.
authors.forename: Sofia
authors.initials: S
authors.lastname: Kordolaimi
authors.affiliation: Medical Physics Department, Hygeia Hospital, Athens, Greece.
authors.forename: Efi
authors.initials: E
authors.lastname: Koutsouveli
authors.affiliation: Medical Physics Department, Hygeia Hospital, Athens, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Sandilos
authors.affiliation: Medical Physics Laboratory, Medical School, University of Athens, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Dimitriou
authors.affiliation: Department of Radiation Oncology, Hygeia Hospital, Athens, Greece.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Dardoufas
authors.affiliation: Medical Physics Laboratory, Medical School, University of Athens, Greece.
authors.forename: Enavgelos
authors.initials: E
authors.lastname: Georgiou
mesh_terms: D006801:Humans; D008297:Male; D055585:Physical Phenomena; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
keywords: Anatomy based; Fluence-based; Prostate; VMAT